Metal complexes are useful as light-emitting materials, and used as materials for organic electroluminescent devices and wavelength converting materials for LEDs. However, many of the metal complexes used as light-emitting materials have low solubility in solvents or resins. For this reason, in the case where a metal complex is used as a light-emitting material, the metal complex is used as a thin film of the metal complex formed by a vacuum evaporation method, for example.
In such circumstances, tris(8-hydroxyquinolinato)aluminum (Alq3), which is one of light-emitting materials for organic electroluminescent devices, receives attention for its high quantum yield and high luminance. Alq3 is expected to be applied as a light-emitting body dispersed in a resin or a wavelength converting material for LEDs. Alq3, however, has problems such as low solubility in solvents and low molecule dispersibility into resins.
In order to solve the problems above, Non Patent Literature 1 proposes a method wherein a ligand having two quinolinol skeletons and an aluminum trisacetylacetonate metal complex are subjected to a ligand exchange reaction in an organic solvent to obtain a polymeric metal complex which can be uniformly dispersed in a solvent such as methylene chloride.